Association of augmentation index of radial pressure wave form with diurnal variation pattern of blood pressure in untreated patients with essential hypertension

OBJECTIVES: The augmentation index of the radial pulse wave has been reported to be a sensitive aortic stiffness marker in relatively young but not in older individuals. We studied the relationship between augmentation index and the diurnal blood pressure profiles. PATIENTS AND METHODS: Twenty-four-hour ambulatory blood pressure monitoring was performed in 90 untreated patients with uncomplicated essential hypertension. The patients were classified into four groups: dippers, extreme dippers, nondippers, and risers. Augmentation index was calculated as the percentage of the second systolic peak relative to the first systolic peak. RESULTS: No significant differences in the averaged whole 24-h systolic or diastolic blood pressure were observed in the whole set of patients or in subgroup patients with age 60 years or under. In the whole set of patients (58.7 ± 12.9 years), there were significant differences in augmentation index between patients with abnormal (other than dippers) and normal diurnal blood pressure profiles (dippers). In subgroup patients with age 60 years or below (49.1 ± 9.1 years, n = 48), the abnormal diurnal blood pressure profile group showed significantly higher augmentation index (89.6 ± 10.3%) than dippers (80.5 ± 11.8%). The area under the curve in the receiver operating characteristics curve for distinguishing between dippers than other dippers was 0.73 (P < 0.01). Multivariate analysis demonstrated that abnormal diurnal blood pressure profile was independently associated with increase in augmentation index. In contrast, these relationships were not significant in the over 60 years subgroup patients (69.8 ± 5.6 years old, n = 42). CONCLUSIONS: The present study revealed that augmentation index was associated with dipping blood pressure patterns in untreated hypertensive patients aged 60 years or younger. Augmentation index determination would be useful for initial assessment in connection with possible abnormal diurnal blood pressure variability in patients with age 60 years or younger.